[PATCH v12 19/25] arm,x86,fs/resctrl: Enumerate AET on every resctrl mount
From: Tony Luck
Date: Wed Sep 16 2026 - 19:25:05 EST
Call resctrl_arch_pre_mount() for every mount protected by
resctrl_mount_lock. Add matching resctrl_arch_unmount() path for
architecture code to clean up on mount failure or unmount.
Remove intel_aet_exit() after moving all the cleanup code into
intel_aet_unmount().
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
v12:
Rest of old patch 17 merged into patch 18 so the umount
code path is complete.
Fix rdt_get_tree() return value when kernfs_get_tree() fails.
Move resctrl_arch_unmount() after cpus_read_unlock() in out: error path
Update resctrl_arch_pre_mount() header comment to say it is now
called for each mount, not just the first.
Update comment for resctrl_mounted to say that both resctrl_mount_lock
and rdtgroup_mutex must be help to change state.
---
include/linux/resctrl.h | 10 ++++++--
arch/x86/kernel/cpu/resctrl/internal.h | 4 ++--
arch/x86/kernel/cpu/resctrl/core.c | 21 +++++++++++++++--
arch/x86/kernel/cpu/resctrl/intel_aet.c | 29 +++++++++++++++++++----
drivers/resctrl/mpam_resctrl.c | 4 ++++
fs/resctrl/rdtgroup.c | 31 ++++++++++++++++++++-----
6 files changed, 82 insertions(+), 17 deletions(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 604ab7af7c2b..5a975856f670 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -590,11 +590,17 @@ void resctrl_online_cpu(unsigned int cpu);
void resctrl_offline_cpu(unsigned int cpu);
/*
- * Architecture hook called at beginning of first file system mount attempt.
- * No locks are held.
+ * Architecture hook called at beginning of each file system mount attempt.
+ * Called while holding resctrl_mount_lock.
*/
void resctrl_arch_pre_mount(void);
+/*
+ * Architecture hook called when mount fails, or on unmount.
+ * Called while holding resctrl_mount_lock.
+ */
+void resctrl_arch_unmount(void);
+
/**
* resctrl_arch_rmid_read() - Read the eventid counter corresponding to rmid
* for this resource and domain.
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index fc60b0af250d..5e71dd758624 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -234,15 +234,15 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
void resctrl_arch_mbm_cntr_assign_set_one(struct rdt_resource *r);
#ifdef CONFIG_X86_CPU_RESCTRL_INTEL_AET
-void __exit intel_aet_exit(void);
bool intel_aet_pre_mount(void);
+void intel_aet_unmount(void);
int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
struct list_head *add_pos);
bool intel_handle_aet_option(bool force_off, char *tok);
#else
-static inline void __exit intel_aet_exit(void) { }
static inline bool intel_aet_pre_mount(void) { return false; }
+static inline void intel_aet_unmount(void) { }
static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val)
{
return -EINVAL;
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 2fa4ebf7159a..3bf4d1a07593 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -811,6 +811,25 @@ void resctrl_arch_pre_mount(void)
cpus_read_unlock();
}
+void resctrl_arch_unmount(void)
+{
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
+ int cpu;
+
+ if (!r->mon_capable)
+ return;
+
+ intel_aet_unmount();
+
+ cpus_read_lock();
+ mutex_lock(&domain_list_lock);
+ for_each_online_cpu(cpu)
+ domain_remove_cpu_mon(cpu, r);
+ r->mon_capable = false;
+ mutex_unlock(&domain_list_lock);
+ cpus_read_unlock();
+}
+
enum {
RDT_FLAG_CMT,
RDT_FLAG_MBM_TOTAL,
@@ -1159,8 +1178,6 @@ late_initcall(resctrl_arch_late_init);
static void __exit resctrl_arch_exit(void)
{
- intel_aet_exit();
-
cpuhp_remove_state(rdt_online);
resctrl_exit();
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 32f3f30894a4..8aa2e18a6bbb 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -298,7 +298,7 @@ static enum pmt_feature_id lookup_pfid(const char *pfname)
/*
* Protects pmt_module, get_feature, put_feature against races between module
* load/unload of the pmt_telemetry module and mount/unmount of the resctrl
- * file system.
+ * file system. Also protects pmt_in_use.
*/
static DEFINE_MUTEX(aet_register_lock);
@@ -306,6 +306,11 @@ static struct module *pmt_module;
static struct pmt_feature_group *(*get_feature)(enum pmt_feature_id id);
static void (*put_feature)(struct pmt_feature_group *p);
+/*
+ * Track whether pmt_telemetry enumeration succeeded during mount for use during unmount.
+ */
+static bool pmt_in_use;
+
/*
* Request a copy of struct pmt_feature_group for each event group. If there is
* one, the returned structure has an array of telemetry_region structures,
@@ -375,19 +380,33 @@ bool intel_aet_pre_mount(void)
return false;
}
+ pmt_in_use = true;
+
return true;
}
-void __exit intel_aet_exit(void)
+void intel_aet_unmount(void)
{
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
struct event_group **peg;
+ guard(mutex)(&aet_register_lock);
+ if (!pmt_in_use)
+ return;
+
for_each_event_group(peg) {
- if ((*peg)->pfg) {
- intel_pmt_put_feature_group((*peg)->pfg);
- (*peg)->pfg = NULL;
+ struct event_group *e = *peg;
+
+ if (e->pfg) {
+ for (int i = 0; i < e->num_events; i++)
+ resctrl_disable_mon_event(e->evts[i].id);
+ put_feature(e->pfg);
+ e->pfg = NULL;
}
}
+ module_put(pmt_module);
+ pmt_in_use = false;
+ r->mon.num_rmid = 0;
}
#define DATA_VALID BIT_ULL(63)
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 69c9e02d2f40..f42f98f89c38 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -121,6 +121,10 @@ void resctrl_arch_pre_mount(void)
{
}
+void resctrl_arch_unmount(void)
+{
+}
+
bool resctrl_arch_get_cdp_enabled(enum resctrl_res_level rid)
{
return mpam_resctrl_controls[rid].cdp_enabled;
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 2e9f71901f68..07fefa3c434e 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -30,6 +30,9 @@
#include "internal.h"
+/* Mutex protecting resctrl_mounted and mount/unmount operations */
+static DEFINE_MUTEX(resctrl_mount_lock);
+
/* Mutex to protect rdtgroup access. */
DEFINE_MUTEX(rdtgroup_mutex);
@@ -48,7 +51,10 @@ LIST_HEAD(resctrl_schema_all);
*/
static LIST_HEAD(mon_data_kn_priv_list);
-/* The filesystem can only be mounted once. */
+/*
+ * The filesystem can only be mounted once. Can only be updated
+ * while holding both resctrl_mount_lock and rdtgroup_mutex.
+ */
bool resctrl_mounted;
/* Kernel fs node for "info" directory under root */
@@ -3149,6 +3155,7 @@ static void resctrl_unmount(void)
{
struct rdt_resource *r;
+ mutex_lock(&resctrl_mount_lock);
cpus_read_lock();
mutex_lock(&rdtgroup_mutex);
@@ -3166,6 +3173,8 @@ static void resctrl_unmount(void)
resctrl_mounted = false;
mutex_unlock(&rdtgroup_mutex);
cpus_read_unlock();
+ resctrl_arch_unmount();
+ mutex_unlock(&resctrl_mount_lock);
}
static int rdt_get_tree(struct fs_context *fc)
@@ -3177,24 +3186,27 @@ static int rdt_get_tree(struct fs_context *fc)
struct rdt_resource *r;
int ret;
- DO_ONCE_SLEEPABLE(resctrl_arch_pre_mount);
+ mutex_lock(&resctrl_mount_lock);
- cpus_read_lock();
- mutex_lock(&rdtgroup_mutex);
/*
* resctrl file system can only be mounted once.
*/
if (resctrl_mounted) {
ret = -EBUSY;
- goto out;
+ goto out_mount_unlock;
}
/* Avoid races from pending operations from a previous mount */
if (atomic_read(&rdtgroup_default.waitcount) != 0) {
ret = -EBUSY;
- goto out;
+ goto out_mount_unlock;
}
+ resctrl_arch_pre_mount();
+
+ cpus_read_lock();
+ mutex_lock(&rdtgroup_mutex);
+
if (!resctrl_alloc_capable() && !resctrl_mon_capable()) {
ret = invalfc(fc, "No allocation or monitoring features are available or enabled");
goto out;
@@ -3289,6 +3301,8 @@ static int rdt_get_tree(struct fs_context *fc)
mutex_unlock(&rdtgroup_mutex);
cpus_read_unlock();
+ mutex_unlock(&resctrl_mount_lock);
+
ret = kernfs_get_tree(fc);
/*
* resctrl can only be mounted once, new superblock only expected
@@ -3297,6 +3311,7 @@ static int rdt_get_tree(struct fs_context *fc)
if (!ctx->kfc.new_sb_created)
resctrl_unmount();
kernfs_put(rdt_root_kn);
+
return ret;
out_mondata:
@@ -3320,6 +3335,10 @@ static int rdt_get_tree(struct fs_context *fc)
out:
mutex_unlock(&rdtgroup_mutex);
cpus_read_unlock();
+ resctrl_arch_unmount();
+out_mount_unlock:
+ mutex_unlock(&resctrl_mount_lock);
+
return ret;
}
--
2.55.0